1. Technical Field
The present invention pertains to improvements in liquid markers and more particularly, to free ink marker systems and methods utilizing pigments, paints, dyes, liquid chalk, etc.
2. Discussion of the Art
Various prior art markers permit marking fluids to be squeezed from a container through a porous nib; however, such markers have lacked the ability to control or modulate the delivery rate as required for detailed drawing, calligraphy, and other detail oriented applications. Moreover, squeeze containers are typically subject to leakage due to pressure variations and temperature changes. Other prior art marker designs utilize ink housed in absorbent fibers and transferred by capillary action to a porous nib.
Conventional liquid markers can only effect differing line widths by using a differently sized and/or configured nibs for each desired line.
It is an object of the invention to provide a liquid marker delivery method and apparatus in which the marker liquid can be squeezed from a container in a manner that permits close control over the delivery rate of the liquid.
It is another object of the invention to provide a liquid marker delivery method and apparatus capable of producing different line widths and effects with a single nib.
The aforesaid objects are achieved individually and in combination, and it is not intended that the present invention be construed as requiring two or more of the objects to be combined unless expressly required by the claims attached hereto.
In accordance with the present invention, a marker system utilizes three primary components to permit the marker to produce lines of various widths from a single nib. The three primary components are a porous nib, a transfer wick and a squeezable container or housing in which the wick and nib are disposed with the nib protruding from one end thereof. Stated otherwise, the present invention combines a porous wick utilized in conjunction with a squeezable plastic tube or bottle and a porous plastic or felt nib. System operation relies on different squeeze pressures applied to the housing to produce different line widths from the single nib. Squeeze bottles without a wick are subject to leakage due to pressure variations and temperature changes. The porous wick of the present invention provides a resistance to flow until the bottle is squeezed and then supplies a minimum of capillary flow to the nib. The wick resistively blocks flow of the marker liquid to the porous nib in the absence of pressurization of the enclosed volume of the housing to a predetermined level above ambient pressure. The user squeezes the container to overcome the resistance of the wick, and can supply marker fluid to the nib at volumes directly related to the squeeze pressure. In response to squeezing or compressing the housing or container to pressurize the enclosed volume to the predetermined level, the capillary flow of the contained marker liquid is delivered from the enclosed volume to the nib. As used herein the terms xe2x80x9cwickxe2x80x9d and xe2x80x9cwick memberxe2x80x9d refer to a device capable of drawing liquid along surfaces thereof (i.e., by virtue of the very nature of its material and the nature of the liquid), or through one or more capillary orifices defined through the member, to provide the liquid delivery requirements described herein.
The simple device of the present invention requires no venting to atmosphere of the container interior because the wick and porous nib system allows the passage of air into the container. The porosity of the porous nib forms an aspiration means for permitting entry of the ambient air into the enclosed volume in response to the pressure in the enclosed volume dropping below ambient pressure. A channel defined in the periphery of the nib and a channel defined in a portion of the housing surrounding the nib also aid the aspiration means. Specifically, when the container is returned to its unstressed (i.e., un-squeezed) condition, ambient air is aspirated back into the container through the nib-wick system.
The squeeze pressure required to emit marker fluid from the container interior is set to be greater than any atmospheric differential pressure that would normally be experienced in the use of the marker system. In this manner, the marker system operates properly in airplanes, at different ground elevations, etc., without leaking due to pressure differentials.
The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following definitions, descriptions and descriptive figures of specific embodiments thereof wherein like reference numerals in the various figures are utilized to designate like components. While these descriptions go into specific details of the invention, it should be understood that variations may and do exist and would be apparent to those skilled in the art based on the descriptions herein.